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Fire Resistance Classes and Test Methods | Fireproof Safes & Vaults

Fireproof safes and fire-resistant cabinets are tested according to international standards that determine how long their contents remain protected during a fire. These fire-resistance tests evaluate factors such as internal temperature limits, duration of fire exposure and the cooling phase after the fire.

The most widely used standards for fireproof safes include EN 1047-1, UL 72, NT Fire 017 and EN 15659. This page explains the different fire-resistance classes and test methods, and compares how these standards protect paper documents and digital storage media.

Understanding these standards helps when selecting a fireproof safe or fire-resistant cabinet that provides the appropriate level of protection.
Two categories: paper and digital media

Fire-resistant classes and test methods

Two categories: paper and digital media

Fire resistance testing distinguishes between two types of contents:

  • Paper: begins to char and deteriorate at temperatures of around 170–180 °C.
  • Digital media (such as hard drives, magnetic tapes and USB sticks): can already be damaged at temperatures from approximately 55 °C.

A certified fireproof safe must keep the internal temperature, both during the fire and throughout the natural cooling phase afterwards, below these critical thresholds.

Lighter standards: NT Fire 017 and EN 15659 (LFS)

The standards NT Fire 017 and EN 15659 are among the most widely used test methods for fire-resistant safes and archival cabinets in Europe.

NT Fire 017

Developed in Scandinavia by Nordtest, this standard is widely used worldwide for fire-resistant archival and data storage cabinets.
The test is carried out in a furnace following the standard time-temperature fire curve (ISO 834 / EN 1363-1), where the temperature reaches approximately 945 °C after 60 minutes.

There are certifications for paper and digital media:

NT Fire 017 Paper
maximum internal temperature 180 °C, protection of paper for 60, 90 or 120 minutes.

NT Fire 017 Data
maximum internal temperature 80 °C, protection of digital media for 60, 90 or 120 minutes.

NT Fire 017 Diskette
maximum internal temperature 60 °C, protection of highly sensitive magnetic media for 60, 90 or 120 minutes.

For the Paper class, a maximum temperature rise of 150 K is permitted. Since the test may start at temperatures of up to 30 °C, the resulting maximum internal temperature is approximately 180 °C.


EN 15659 (LFS – Light Fire Storage)

EN 15659 is a European standard for light fire-resistant storage units and represents a less demanding test than EN 1047-1.
The standard is developed within CEN (European Committee for Standardization) and certifications are issued, among others, by ECB·S.

The test is also performed according to the standard time-temperature fire curve (ISO 834 / EN 1363-1), where the furnace temperature reaches approximately 842 °C after 30 minutes and 945 °C after 60 minutes.

This standard applies exclusively to paper protection.

LFS 30
maximum internal temperature 172 °C, protection of paper for 30 minutes.

LFS 60
maximum internal temperature 172 °C, protection of paper for 60 minutes.

The standard defines a maximum temperature rise of 150 K. Since the test starts at approximately 20–22 °C, this results in a maximum internal temperature of about 172 °C.


Limitations of light fire standards

In NT Fire 017 and EN 15659, the test stops once the specified test time has been reached.
The safe is then removed from the furnace and artificially cooled, meaning that the natural cooling phase of a real fire is not simulated.

In a real fire, however, a safe may remain hot for many hours, which can cause the internal temperature to continue rising, potentially damaging the contents.

Standards such as EN 1047-1 and UL 72 take this into account by including an additional cooling test, where the internal temperature must remain below the permitted limit even after the fire has ended.

Stricter standards: EN 1047-1 and UL 72

The standards EN 1047-1 and UL 72 are among the strictest and most reliable fire-resistance tests for fireproof safes, fireproof cabinets and archival storage cabinets, because they simulate not only the fire itself but also its consequences, including the natural cooling phase.


EN 1047-1

EN 1047-1 is a European standard for fireproof safes, data safes and fire-resistant archive cabinets, and is considered the strictest European standard for the fire protection of paper documents and digital data media.

The test consists of several stages.

Fire test

The fireproof safe is exposed for 60 or 120 minutes to a furnace that follows the standard time–temperature fire curve (ISO 834 / EN 1363-1).


Impact and fire shock test

To simulate a realistic fire scenario, an additional test is carried out.

The safe is first placed in a furnace already heated to approximately 1090 °C.
The fireproof safe is then dropped from a height of about 9.15 metres onto a bed of rubble, simulating the collapse of a building.

Afterwards, the safe is returned to the furnace and heated again. Once the fire test has ended, the safe must cool down naturally, while the internal temperature continues to be monitored.

This procedure simulates a realistic situation in which a building collapses during a fire and the fireproof safe or fireproof cabinet remains exposed to high temperatures for an extended period.


Classifications

S60P / S120P
protection of paper documents – maximum internal temperature 172 °C

S60D / S120D
protection of digital data media – maximum internal temperature 72 °C

S60DIS / S120DIS
protection of highly sensitive data media – maximum internal temperature 52 °C


UL 72

UL 72 is an American standard for fireproof document safes, archive cabinets and data safes, and is conceptually comparable to EN 1047-1.

During the test, the fireproof safe is exposed for ½, 1, 2, 3 or 4 hours to a furnace that also follows the standard time–temperature fire curve.


Classifications

Class 350
protection of paper documents – maximum internal temperature 177 °C

Class 150
protection of microfilm and magnetic media – maximum internal temperature 66 °C

Class 125
protection of highly sensitive digital media – maximum internal temperature 52 °C


In UL 72, an impact test (drop test) may be included in the procedure, but it is optional. As with EN 1047-1, a natural cooling phase is applied in which the temperature inside the fireproof safe continues to be monitored after the fire test has ended.


Importance of natural cooling

In a real fire, a fireproof safe or fireproof cabinet often cools down only several hours after the fire has been extinguished, and the internal temperature may continue to rise for some time.

Only standards such as EN 1047-1 and UL 72 explicitly test this cooling phase (“cooling test”). This ensures that the contents of the fireproof safe remain protected even after the fire itself has ended.

For this reason, these standards offer the highest level of fire protection, not only during the fire but also during the critical hours afterwards.

Standards That Provide No Guarantee

Certain standards such as DIN 4102 and BS 476 relate only to the fire reaction of construction materials and were not designed for safes or security cabinets. DIN 4102 essentially means that the material itself is non- or low-combustible, but it says nothing about the protection of the contents in the event of a fire.

References such as “according to DIN 4102” should never be mistaken for a true fire resistance test: such a safe does not protect the contents against fire. If you are offered a fireproof cabinet certified only to DIN 4102, do not hesitate to request a test report.

For reliable protection, one should only rely on safes and fireproof cabinets tested according to recognised standards such as NT Fire 017, EN 15659, EN 1047-1 and UL 72.

Comparison of fire-resistance standards for safes and fireproof cabinets

Standard / class Protection Maximum internal
temperature
Test duration (min) Cooling Drop test
EN 1047-1 S60P Paper 172 °C 60 Yes Yes
EN 1047-1 S120P Paper 172 °C 120 Yes Yes
EN 1047-1 S60D Digital media 72 °C 60 Yes Yes
EN 1047-1 S120D Digital media 72 °C 120 Yes Yes
EN 1047-1 S60DIS Sensitive data 52 °C 60 Yes Yes
EN 1047-1 S120DIS Sensitive data 52 °C 120 Yes Yes
UL 72 Class 350 Paper 177 °C 30–240 Yes Optional
UL 72 Class 150 Digital media 66 °C 30–240 Yes Optional
UL 72 Class 125 Sensitive data 52 °C 30–240 Yes Optional
NT Fire 017 Paper Paper 180 °C 60–120 No No
NT Fire 017 Data Digital media 80 °C 60–120 No No
NT Fire 017 Diskette Sensitive data 60 °C 60–120 No No
EN 15659 LFS 30 Paper 172 °C 30 No No
EN 15659 LFS 60 Paper 172 °C 60 No No

Summary

Standards such as EN 1047-1 and UL 72 are considered the most stringent because they include a natural cooling phase after the fire test. This ensures that the contents of a fireproof safe or fire-resistant cabinet remain protected even after the fire itself has ended.

The standard fire curve

Fireproof safes and fire-resistant cabinets are tested in furnaces that follow a standardised time–temperature fire curve.
In Europe this curve is defined in EN 1363-1 and internationally it is known as the ISO 834 fire curve.

This curve simulates the development of a typical building fire, where materials such as wood, paper and furniture are burning.

During the test, the furnace temperature rises very rapidly. Typical values according to this fire curve are:

Time Furnace temperature
5 min approx. 576 °C
10 min approx. 679 °C
30 min approx. 842 °C
60 min approx. 945 °C
90 min approx. 1006 °C
120 min approx. 1049 °C

This fire curve is used in most international standards for fireproof safes and fire-resistant cabinets, including EN 1047-1, EN 15659, NT Fire 017 and UL 72.

Reliability of certifications

Only safes tested by independent, accredited laboratories and certified by organisations such as ECB·S (European Certification Body) provide a reliable guarantee of the declared fire resistance.

Find out more about burglar-resistance classes and test methods

Further information and sources

For more information about fire-resistance standards and testing methods for fireproof safes and fire-resistant cabinets, you can consult the following organisations:

These organisations publish standards and certifications used for fireproof safes and fire-resistant cabinets.

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